As LSI circuits are increasing in density, circuit linewidths of semiconductor devices are becoming finer. In manufacturing a semiconductor device, an exposure mask (also called a reticle, which is used in a stepper or a scanner) having a circuit pattern is used. An exposure apparatus transfers the pattern to a wafer.
Examples of factors that reduce the yield of manufacturing semiconductor devices include a defect of a pattern formed on a mask or a wafer. There is a need to accurately inspect pattern defects. For example, a known apparatus inspects patterns on a sample for defects by irradiating the sample with a plurality of electron beams (multiple beams) and allowing a detector to detect reflected electrons or secondary electrons released from the sample. The use of multiple beams provides higher throughput of defect inspection than an inspection apparatus using a single electron beam (single beam).
A detector accumulates charges attributable to reflection electrons or secondary electrons that are received by the same, and takes out those charges as an electrical signal. Because an amount of the accumulated charges attributable to the reflection electrons or the secondary electrons is small, the accumulated charges are preferably read out with a low-speed and high-sensitivity detection circuit in order to increase inspection accuracy. However, the reflection electrons or the secondary electrons cannot be received and detected during reading of the charges. Thus, there has been a problem that the reading of the charges with the low-speed and high-sensitivity detection circuit reduces the throughput of inspection.